package org.apache.solr.core;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.io.IOException;

import org.apache.lucene.index.IndexReader;
import org.apache.lucene.store.Directory;
import org.apache.solr.common.util.NamedList;
import org.apache.solr.util.plugin.NamedListInitializedPlugin;

/**
 * Factory used to build a new IndexReader instance.
 */
public abstract class IndexReaderFactory implements NamedListInitializedPlugin {
	protected int termInfosIndexDivisor = 1;// IndexReader.DEFAULT_TERMS_INDEX_DIVISOR;
											// Set this once Lucene makes this
											// public.

	/**
	 * Potentially initializes {@link #termInfosIndexDivisor}. Overriding
	 * classes should call super.init() in order to make sure
	 * termInfosIndexDivisor is set.
	 * <p>
	 * <code>init</code> will be called just once, immediately after creation.
	 * <p>
	 * The args are user-level initialization parameters that may be specified
	 * when declaring an indexReaderFactory in solrconfig.xml
	 * 
	 */
	public void init(NamedList args) {
		Integer v = (Integer) args.get("setTermIndexDivisor");
		if (v != null) {
			termInfosIndexDivisor = v.intValue();
		}
	}

	/**
	 * 
	 * @return The setting of {@link #termInfosIndexDivisor}
	 */
	public int getTermInfosIndexDivisor() {
		return termInfosIndexDivisor;
	}

	/**
	 * Creates a new IndexReader instance using the given Directory.
	 * 
	 * @param indexDir
	 *            indexDir index location
	 * @param readOnly
	 *            return readOnly IndexReader
	 * @return An IndexReader instance
	 * @throws IOException
	 */
	public abstract IndexReader newReader(Directory indexDir, boolean readOnly)
			throws IOException;
}
